1. Field of the Invention
This invention relates broadly to mechanisms for igniting fuel in a combustion chamber. More particularly, this invention relates to ignitor plugs that utilize resistive heating to ignite a combustible fuel supplied thereto.
2. State of the Art
Small turbine engines and other rotary engines commonly utilize an ignitor plug employing resistive heating to ignite a combustible fuel in a combustion chamber. The resulting flame produced by the burning fuel in the combustion chamber ignites heavy liquid fuel that is introduced into the combustion chamber. The combustible fuel supplied to the ignitor plug is then shut off, and the engine continues to run on the heavy liquid fuel supplied to the combustion chamber. This type of ignitor plug is typically referred to as a glow plug, examples of which are sold commercially under the trade name O.S. Engines by Great Planes Model Distributors of Champaign, Ill.
As the resistive heating employed by prior art glow plugs will not ignite heavy liquid fuels that are required to run the engine, an additional fuel system is required to start the engine. The additional fuel system significantly increases the operational cost and weight of such engines. Glow plugs that ignite heavy fuel have been utilized in large diesel engines to heat the combustion air to aid in starting the engine. However, these prior art glow plugs typically use high amperage D.C. voltages, are very large and heavy, and are not compatible with small-size turbine engines. In addition, they are subject to coking of the fuel path through the igniter plug, which reduces the operational lifetime of the igniter plug and increases the operational costs of such engines.